A RANS Based Method for the Estimation of Ship Roll Damping With Forward Speed

For the prediction of ship roll motion, viscous effects must be taken into account. Several methods, experimental and theoretical, have previously been used to calculate hydrodynamic forces in roll motion. Theoretical methods applied so far to this problem have been based mainly on potential flow models, which cannot account for viscous effects adequately or need pre-defined flow separation like vortex methods. Recent development of computer hardware enables application of methods based on flow field discretisation such as finite-difference methods to solution of problems of practical ship design such as ship motions and control. In the present study, a Reynolds-Averaged Navier-Stokes solver is used to calculate hydrodynamic loads during forced roll motion at different Froude numbers. The solution method adopted is based on unstructured finite-volume discretisation with collocated arrangement of flow variables. A pressure-correction algorithm (SIMPLE) is used for the pressure-velocity coupling. A standard k–ε model is used for the turbulence modeling. An advanced differencing scheme called high-resolution interface capturing (HRIC) is used for accurate resolution of the free surface in the scope of a multiphase-type description. A high-speed hard chine vessel with and without skeg is studied. Close agreement is found between the present calculations and experimental results.